Hypertension and the associated renal and cardiovascular complications are a serious health problem in the Unites States. Approximately 65% of hypertensive patients do not have their blood pressure controlled and women are more likely than men to have uncontrolled blood pressure. The renin-angiotensin system (RAS) is a key system in controlling blood pressure. RAS inhibitors are among the most commonly prescribed drugs for the treatment of hypertension and renal disease, although available data suggests that RAS inhibition does not confer the same degree of cardio-renal benefit in women and men. The objective of this proposal is to determine the molecular mechanisms by which activation and inhibition of the RAS regulate hypertension and renal injury in females and males. We hypothesize that sex differences in functional responses to RAS activation and inhibition are related to (1) a differential balance in females and males in the activation of the classical RAS, which induces hypertension and renal injury, vs. the non-classical RAS, which promotes cardiovascular health, and (2) sex differences in RAS activation of signaling molecules. Three Specific Aims will test our hypotheses. Specific Aim 1 will test the hypothesis that females have greater expression and activation of the non-classical RAS which attenuates RAS-mediated hypertension and renal injury compared to males. We will measure expression levels of the classical and non-classical RAS components at baseline and following RAS stimulation in male and female spontaneously hypertensive rats (SHR) and in normotensive rats (WKY). We will measure blood pressure to determine if increased non-classical RAS activation in female SHR accounts for (1) the imbalance in females to RAS activation and blood pressure and (2) sex differences in the effectiveness of classical RAS inhibitors. We will assess the sensitivity of kidneys in males and females to RAS stimulation, as the kidney is important in the long-term control of blood pressure. Specific Aim 2 will test the hypothesis that female SHR have greater RAS-stimulated nitric oxide (NO) bioavailability in the renal cortex compared to male SHR. NO is an important regulator of renal health. We will determine the ability of the RAS to regulate NO bioavailability in male and female SHR. We will measure blood pressure to determine if RAS-mediated NO contributes to sex differences in L-NAME hypertension. Specific Aim 3 will test the hypothesis that AT1 activation results in the production of different signaling molecules in the renal cortex of male and female SHR, focusing on superoxide, transforming growth factor-2, and Janus kinase/signal transducers and activators of transcription. We will determine the effects of RAS activation on the levels of these factors in the renal cortex of male and female SHR, and their contribution to RAS mediated hypertension and renal injury. These studies may provide the basic science framework to develop more personalized and more effective therapeutic options for the treatment of hypertension and the prevention of chronic kidney disease in men and women.